This also introduces a link to the core membership policy which we
refer to elsewhere in the document.

The policy was marked as "draft" in the document, but classified as
"standard" in the list because the deadline had expired without
objection, so it technically *was* standard.

In any case, it was implemented and now is therefore obsolete (because
it's useless to keep such an historical proposal forever).

They were called "lists" and "milestones" before. We don't use "list"
because we use the word "list" to list the queues in the
documentation, so it would be confusing. That might be a bad idea.

Without it, the "Open" queue has a lot of junk and new tickets get
lost in the noise. By moving most of that junk in the Icebox queue,
new tickets immediately pop up in the Open queue and can be properly triaged.

We add the Next label because it's already being used in a subproject
of tpa (gitlab) and because it's used globally. It also helps us
separate the "endless pile of ticket" in Open from the Backlog, as
now we can throw more things in the backlog without worrying about
overloading our monthly capacity.